As we all know this gun was discussed in the Antiques section recently, and personally I just don't see it as a product of Joe Long.
First, the L in the signature initials is nothing like the L of Joe Longs signature, at least of those of the several Joe Longs that I've seen.
The patchbox is not similar either. J. Long boxes seem to be more refined as to overall shape and execution, with the brass around the side plate and finale cutouts more slender and delicate. Long also seemed to use two screws in the finale near the hinge, and the nails he used in the box much smaller. The two Longs that I owned both had a five segment hinge, where this one only has a three segment hinge. Long wasn't much of an engraver and I don't remember seeing one of his rifles with an engraved patchbox lid, but the Long swivel rifle I had did have engraving on the side plate opposite the lock and it was pretty folksy, so Ill hold my opinion on this engraved lid.
This rifle has rectangular inlays running down the forearm, where as J. Long seems to prefere the long teardrops, or at least I've seen them on a number of his guns.
Also, Joe Longs stock work seemed to have a more refined architecture than this rifle, and that adds another doubt to my mind.
The forum guys seemed to think it maybe a George Long, or maybe a Loudenslager. Maybe, I can't say either way. I just don't think it a product of Joseph Long.
It's a pretty rifle with better architecture than found on most guns from that area. It has nice sleek lines and the workmanship is good. It would be nice to identify who the maker is, as it does not appear to have been Long. Put it in the Library and perhaps someone will come along who does know.
I repeat, we need a "NOS" category just like our medical bretheren in psychiatry. When a real piece of work comes in the door that they can't classify with a definite DSM diagnosis, they simply grin and label it NOS...not otherwise specified.
I think it is safest to call it an Unknown Upper Susquehanna, as there is no clear answer. Long never engraved, except for the eyes on fish, rarely, and there is nothing else that points this in the direction of Long , except for the football side plate. I think the safer bet, if I had to guess is J. Laudenslager, who is otherwise not very well documented with anything I can safely say is a J. Laudenslager, for sure. The engraving is rather primitive and that is similar to other Laudenslagers. George Long is another possibility with the square forestock inlays, which seems late.